Kirstie Alley Fell in Love With Patrick Swayze, John Travolta While Married to Parker Stevenson

While promoting her new book, Alley also opened up about the affair that led to her first divorce, from high school sweetheart Bob Alley.

With a new book to promote, Kirstie Alley is making the interview rounds, where she has been opening up about her history of infidelity.

The actress, who penned The Art of Men (I Prefer Mine al Dente), has been giving a series of interviews to 20/20's Barbara Walters and Entertainment Tonight's Chris Jacobs, among others, during which she has revealed she fell in love with co-stars Patrick Swayze and John Travolta.

Of Swayze, with whom Alley starred in North and South, the actress said the two had an immediate attraction. Despite her best efforts to avoid "going down that road," she told Jacobs, the two fell in love. At the time, she was married to Parker Stevenson and he was married to Lisa Niemi.

"We did not have an affair," she said. "But again, I think what I did was worse. Because I think when you fall in love with someone when you're married, you jeopardize your own marriage and their marriage. It's doubly bad."

Meanwhile, Alley told Walters that her Look Who's Talking co-star Travolta is the "greatest love" of her life. Still, she resisted temptation because of her marriage to Stevenson, to whom she was married from 1983-97.

"Believe me, it took everything that I had, inside, outside, whatever, to not run off and marry John -- and be with John for the rest of my life," she said, via Huffington Post.

Alley also confessed to ET that she had an affair while married to her first husband, Bob Alley, who was her high school sweetheart. (The two were wed from 1970-77.) While she didn't have sex with the man, whom she identified only as Jake, things did get physical.

"I didn't have sex, but I think it was worse when you fall in love with someone else, when you're with someone, and you're plotting and you're planning," she said. "What I did do with Jake was I kissed him. And in my world, in Kirstie world, that meant I had to get a divorce. ... It took a long time [to forgive myself] because I was a horrible person, I destroyed my marriage."

Alley is currently competing on the all-stars edition of ABC's Dancing With the Stars. Her book hit stores Tuesday.